1. Field of the Invention
The present invention relates to a device for connection between the respective conductors of two cables which can undergo rotational and/or translational movements one with respect to the other, this device including at least one series of sliding contact elements which are linked respectively to the conductors of one of the cables and carried by one support, and at least one other series of sliding contact elements which are linked respectively to the conductors of the other cable, in sliding contact, respectively, with the sliding contact elements of the first series mentioned and carried by another support, which is able to move with respect to the first support mentioned.
The invention may be used in various applications, in all cases when it is necessary to pass a current, small or large, two-phase, three-phase, etc., with or without an earth, between the conductors of two cables, one of these cables being fastened to a structure which is able to move translationally and/or rotationally with respect to the structure to which the other cable is fastened.
An application more particularly, but not exclusively, intended by the present invention is that in which it is desired to supply current, for example heating (de-icing) current, to the blades of a helicopter tail rotor, which requires use of a rotary output terminal block, this being based on a power cable which itself is able to move translationally, being fastened to the servocontrol rod for changing the pitch of the blades, passing through the hub of this tail rotor.
The connection device intended to fulfil these functions will be subjected to a harsh operating regime, a helicopter tail rotor being able to rotate at a speed of about 1250 rpm and the control rod for changing the pitch of the blades being able to move translationally with an amplitude of .+-.40 mm, at a speed of approximately 120 mm/s and at a frequency of a few Hz.
2. Description of the Prior Art
Currently, in certain helicopters fitted with electrical equipment for protecting the blades from ice deposition, the electrical de-icing sleeving is located outside the helicopter rotor and transports the energy, necessary for electrothermally protecting the blades, from the commutator of the rotor hub. Energy is transferred from inside the helicopter to the outside by means of an electrical commutator which combines a stationary part and, fixed to the latter, the rotating part, rings provided with brushes fulfilling this function.
The commutator of the tail rotor blades is fitted around the drive shaft of the hub of the tail rotor, making maintenance on it difficult. This is because any removal of the commutator requires dismantling the rotor shaft in the workshop using suitable tools, hence incurring considerable cost and maintenance time. In addition, on account of the external diameter of the commutator, the latter is designed for high peripheral velocities at the rings and brushes, hence increasing the wear of these components. Power is brought, on the outside, from the commutator to the blades via electrical sleeving subjected to aerodynamic stresses (centrifugal force, vibrations, movement of the blades, translational movement of the blade-pitch-control spider, etc.) due to the sleeving passing along through the various zones.
In order to minimize the maintenance problems and to decrease the stresses in the sleeving, the object of the invention is therefore to construct an entirely fitted-out and modular electrical connection device.
In order to avoid removing the hub and returning it to the workshop in the event of a failure, the object of the invention is also to make it possible to fit this connection device inside the tail rotor hub. In order for this to be accomplished, this connection device must not only be able to be contained in the hub but must also be able to follow, on its input side, the translational movement of the aforementioned servocontrol rod and to follow, on its output side, the rotation of the tail rotor to be supplied with current, as already indicated above.